In my previous U.S. Pat. No. 4,377,365 issued Mar. 22, 1983, there is disclosed apparatus for handling padding material. Reference is made to my previous U.S. Pat. No. 4,377,365 as well as the art cited therein. Reference is also made to U.S. Pat. Nos. 3,981,089 and 4,057,917 (N. B. Burrows), and to the art cited therein for still further background of this invention.
In the building of cross country pipelines, it is customary for the ditch digging apparatus to form the ditch in advance of the subsequent pipe laying operation. The pipe is layed into the ditch as soon as possible after the excavation operation to avoid the ditch caving and contaminating the pipe with harmful debris. It is therefore desirable to cover the pipe with suitable padding material as soon as the pipe has been layed, and to lay the pipe as soon as the ditch has been dug.
As evidenced by the above prior art, padding material often is especially prepared and transported many miles in order to provide the pipe with proper padding material. It is therefore desirable that the costly step of transporting padding material from a location removed from the pipeline job be eliminated so as to avoid the enormous cost associated therewith. Furthermore, it is desirable that the padding operation be carried out immediately following the pipe laying operation. Further, it is considered advantageous to return similar or compatible material into the ditch which is consistent with the geological characteristics of the geological formation through which the pipeline is formed.
Apparatus and method by which excavated material is processed to obtain suitable padding material for a pipeline, while the residual excavated material is returned to its previous location adjacent to the ditch, is the subject of the present invention.